What would cause my standard Dodge 09 truck to shift by itself to 4th gear?

I have a 2009 Dodge 1500 4x4 had trans rebuilt 10,000 miles later driving @
70 mph truck goes into 4th gear & stay's there couldn't go to any other, I
turned off truck waited like 2 minutes & then turn back on when i put in drive
went to drive  no other issues then a month later did same thing again &
repeated same action's this has happened now 4 time's // Could it be the
shift solenoid overheating or malfunction? When driving at high rate of
speed? i mean 65 mph is NYS law but when you need to pass well you
know.
I had it checked out by a local shop with comp. stated was coming back with
trans related 4th gear code/ i went & got truck while dring it home the check
engine light went out only thing on was *Traction & ABS*// truck runs like a
champ besides those two lights on & even when check engine light was on.
I read rear speed sensor's will do same thing ??